1. Field of the Invention
This invention pertains to new compositions of matter, their synthesis and biological use.
2. Description of the Prior Art
Wiley, R. H., and Guerrant, W. B., JACS, 71, 981 (1949) describe the formation of diamides from carboxylic acids and their nitriles. The reference discloses that heating together equimolar amounts of phenylacetic acid or p-nitrophenylacetic acid and their nitriles at temperatures up to about 250.degree. C produces good yields of diamide. The reactions are carried out under oxygen free nitrogen to prevent discoloration and temperatures employed are below the atmospheric boiling point of the carboxylic acid reactants. However, the literature appears to be devoid of references to similar transformations of polyhaloaromatic nitriles, especially pentachlorobenzonitrile.
In a rather extensive investigation into the chemistry of pentachlorobenzonitrile and its derivatives, I have discovered that the reactions of these compounds are generally unpredictable. For example, there are classical methods known in the art to effect the conversion of nitrile derivatives to amide derivatives, such as mixing and reacting a nitrile with hot caustic, hot alcoholic caustic, mixtures of phosphoric and acetic acids, and the like. However, experiments have shown that the classical methods fail to effect the conversion of polychlorobenzonitrile derivatives to corresponding polychlorobenzamide derivatives, especially pentachlorobenzonitrile. Only a single example is known wherein a reagent attacks the cyano group. As described in my copending application, "Novel Process for Preparing Polyhalobenzamide Derivatives", Ser. No. 379,545, filed concurrently herewith, now abandoned. I have found that the treatment of polychlorobenzonitrile derivatives, especially pentachlorobenzonitrile and hydroxy-tetrachlorobenzonitrile, with concentrated sulfuric acid at elevated temperatures produces a resultant corresponding polychlorobenzamide derivative in near quantitive yields.
It was quite surprising, in view of these facts, to discover that N-acetyl-polychlorobenzamide compounds are produced by the treatment of corresponding polychlorobenzonitrile derivatives with acetic acid in a closed reactor at an elevated temperature above the atmospheric boiling point of the acetic acid at autogenous pressure. This was especially surprising in view of my observations that treatment of pentachlorobenzonitrile with a mixture of acetic and phosphoric acids produces no reaction products and that the treatment of pentachlorobenzonitrile with sodium acetate results in aromatic nucleophilic substitution with the cyano group being unreacted. That is to say, as also disclosed in my abovementioned copending application Serial No. (AL-1966) experiments have shown that the treatment of pentachlorobenzonitrile with sodium acetate at elevated temperatures results in the production of acetoxy-tetrachlorobenzonitrile which is essentially converted to the free acid form hydroxy-tetrachlorobenzonitrile by acid addition. In fact, as more particularly described hereafter, the novel compound N-acetyl-pentachlorobenzamide was first discovered in an attempt to produce chlorine-substituted acetoxy-benzonitriles. In carrying out the experiment a mixture of pentachlorobenzonitrile, sodium acetate, acetic anhydride and acetic acid was heated in a sealed vessel at a temperature above the boiling point of the acetic acid. Most unexpectedly, analysis of the resulting isolated precipitate showed that it was N-acetyl-pentachlorobenzamide.